Fletcher's Baja 5B SBK chronicles

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fletcher

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13
Location
Alameda, CA
Hiiii guys-

I've been out of RC cars for a long time. Last car was a Tamiya Hornet in the mid 80's! Man did I have fun building, driving, tuning, and rebuilding that thing... in like the 7th grade. Visiting the local hobby shop all the time. Great times. I bet it's lurking over in Mom's basement somewhere still... I really should take a look.

I've glanced at the RC sites every few years - but either nothing struck a chord, or I was just too busy.

Well I just turned 50 and have a whole garage to tinker around in now, so it's time revisit those good times.

I'm finishing up doing a frame-off restomod build of 1975 Honda Z50 Mini Trail minibike.

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You can read "Fletcher's Z50 chronicles over here if you're interested at all: https://www.planetminis.com/threads/fletchers-z50-chronicles.255461/


So I need a new project to build, and here I am back into RC cars 30 something years later. I have a hunch there's either a lot of us coming back from those days... or there will be soon.

Once of the things that kept me out was electric cars seemed a bit like... toys? A lot had changed. So many cars come already built. What kind of fun is that? The style of the cars didn't jive with my sensibilities. And the wheel transmitters... meh.

I saw that HPI had re-released the Baja 5B as a kit... that thing just screamed gnarly out to me... and down the rabbit hole of hours of research I went.

And here I am with a big old pile of parts...

HPI Baja 5B SBK
Zenoah G320RC 32cc engine
Victory R/C Pro Side-Mount exhaust, non-silenced
Savox-0235MG servo
Hitech D645MW servo
6v DDM Ni-Mh receiver battery pack
Hitec RDX1 charger
Madmax Super Hog tires
Futaba 4GRS Transmitter (sticks 4 life!)
Futaba Transmitter reachargable battery pack+charger
Futaba neck lanyard
VP Racing Powermix gas


Let's. do. this.

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Thanks John! I have no idea what I'm doing!

And exactly why I'm detailing everything here, so people can tell me I'm crazy and point me in the right direction. :cool:

Is the 6v DDM Ni-Mh receiver battery pack wrong... wont work?

I didn't know there was a lipo servo... thought lipo just referred to the battery type/chemistry.
 
i agree with john above fella ☝️(y),
one thing i see missing from the list is a killswitch though, grab one before ya run it (y)
 
Perfect. Thanks guys!

How does this battery sound?
https://www.ddmracing.com/DDM-Racing-7.4v-4000mAh-RX-LiPo-Battery

Or is there a better one you can recommend? Reading between the lines, a lipo receiver battery is higher voltage and can power higher voltage compatible servos better... faster... more responsive?

I'm just wrapping my head around the killswitch idea, and I'm sure there's other things I need to know about, learn, and get.

How are these?
https://www.ddmracing.com/Dynamite-DYNE1240-Large-Scale-Safety-Kill-Switch

https://www.ddmracing.com/MOD-5th-scale-kill-switch

https://www.killerrc.com/collections/kill-switches/products/super-bee-kill-switch-car-kit
 
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fletcher said:
Thanks John! I have no idea what I'm doing!

And exactly why I'm detailing everything here, so people can tell me I'm crazy and point me in the right direction. :cool:

Is the 6v DDM Ni-Mh receiver battery pack wrong... wont work?

I didn't know there was a lipo servo... thought lipo just referred to the battery type/chemistry.
Click to expand...
By "LIPO Servos" John is saying the servos are rated for use with a 2s LIPO battery which has a nominal voltage of 7.4v. The 6v NIMH just won't cut it.
 
Uhhhh ... those aren't LIPO specific servos. If these guys commented read the specs, they work all the way down to 4.8v and obviously there are not "LIPO" servos. Just servos that work within a specific voltage range; they don't give a rats ass about the chemistry. Spot on.

You're not doing anything wrong :) 6v will absolutely cut it for those servos. You do not need hefty servos with "100KG" of torque for the 5B. You need 35-40KG, maybe slightly more if you're adding extra weight to it. The throttle servo is a standard size servo, and again you don't need anything more than 35KG on that either.

6v is perfectly fine :) As a matter of fact, I just picked one up myself and decided against a LIPO in the battery box as the box was designed for a NIMH hump pack. I ended up going for the 6V DDM NIMH battery I ordered just yesterday. I use LIPO only for things that require the absolute most torque you can obtain; otherwise I use LIFE 2s 6.6v batteries extensively for airplane use, and something basic like this 5B I use what it was designed around. You'll have telemetry on your Futaba radio there. You just don't want to go below 0.9v per cell (5.4v) and I'd set my cutoff for below 6v personally. On a full charge you'll see up to and over 8v on a NIMH pack (around 1.45 or so volts per cell).

So you'll be running "LIPO" voltage on a fresh charge. Two servos in proper spec range for this buggy don't draw too much amperage ... you'll get more than enough runtime out of that DDM pack and the servos will work just fine :)

Sorry for the rant ... I hate seeing that poop commented when people buy things that are just fine.
 
codeman11 said:
Uhhhh ... those aren't LIPO specific servos. If these guys commented read the specs, they work all the way down to 4.8v and obviously there are not "LIPO" servos. Just servos that work within a specific voltage range; they don't give a rats ass about the chemistry. Spot on.

You're not doing anything wrong :) 6v will absolutely cut it for those servos. You do not need hefty servos with "100KG" of torque for the 5B. You need 35-40KG, maybe slightly more if you're adding extra weight to it. The throttle servo is a standard size servo, and again you don't need anything more than 35KG on that either.

6v is perfectly fine :) As a matter of fact, I just picked one up myself and decided against a LIPO in the battery box as the box was designed for a NIMH hump pack. I ended up going for the 6V DDM NIMH battery I ordered just yesterday. I use LIPO only for things that require the absolute most torque you can obtain; otherwise I use LIFE 2s 6.6v batteries extensively for airplane use, and something basic like this 5B I use what it was designed around. You'll have telemetry on your Futaba radio there. You just don't want to go below 0.9v per cell (5.4v) and I'd set my cutoff for below 6v personally. On a full charge you'll see up to and over 8v on a NIMH pack (around 1.45 or so volts per cell).

So you'll be running "LIPO" voltage on a fresh charge. Two servos in proper spec range for this buggy don't draw too much amperage ... you'll get more than enough runtime out of that DDM pack and the servos will work just fine :)

Sorry for the rant ... I hate seeing that poop commented when people buy things that are just fine.
Click to expand...
The savox 0235mg has been known to have “brown outs” and glitches when the voltage drops below a certain point. There are even websites that advertise this in the description of the servo. That is why I run them off a LIPO battery. I would rather keep control and not risk glitches.
fletcher said:
Perfect. Thanks guys!

How does this battery sound?
https://www.ddmracing.com/DDM-Racing-7.4v-4000mAh-RX-LiPo-Battery

Or is there a better one you can recommend? Reading between the lines, a lipo receiver battery is higher voltage and can power higher voltage compatible servos better... faster... more responsive?

I'm just wrapping my head around the killswitch idea, and I'm sure there's other things I need to know about, learn, and get.

How are these?
https://www.ddmracing.com/Dynamite-DYNE1240-Large-Scale-Safety-Kill-Switch

https://www.ddmracing.com/MOD-5th-scale-kill-switch

https://www.killerrc.com/collections/kill-switches/products/super-bee-kill-switch-car-kit
Click to expand...
That battery from DDM should fit the bill. As far as kill switches, I have only used the super bee. It works flawlessly. I have mine set up on my aux channel so I can kill the motor on command. It will also kill the motor if voltage drops below an adjustable point or if you lose radio signal. It connects to the motor right where the existing “kill button” is.
 
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When the baja came out...there was no lipo batteries and not even kill switches! If you run at a local track/club you need to have a kill switch. If your just running around your own place your choice. I bought my baja 5b in 2008, still running the nimh and not even a kill switch, never an issue, no glitch or run always, I even had a 27mh crystal radio at first then changed for the spectrum when telemetry came out ( didn't need that either ) just charge your pack before a weekend of running, and after a couple years check to see how many milli amps go in so you know if its losing capacity. That being said I just built a vekta.5 and put a lipo and a kill switch, two steering servos and a 1/5 scale servo for throttle/brake. So maybe I'm learning or getting scared? My primal rc mega truck came with a kill switch and good thing, its ran away three times before I burned 1 tank.
 
Ferrebee88 said:
The savox 0235mg has been known to have “brown outs” and glitches when the voltage drops below a certain point. There are even websites that advertise this in the description of the servo. That is why I run them off a LIPO battery. I would rather keep control and not risk glitches.

That battery from DDM should fit the bill. As far as kill switches, I have only used the super bee. It works flawlessly. I have mine set up on my aux channel so I can kill the motor on command. It will also kill the motor if voltage drops below an adjustable point or if you lose radio signal. It connects to the motor right where the existing “kill button” is.
Click to expand...

The warning about Savox servos are about certain combinations of receiver and ESC generally as is the wording directly on the sites; but IMO personally I don't touch Savox servos kind of like I don't touch Spektrum stuff. The battery is fine, and it's rated capacity is 5,000mah which is way more than enough for those 2 servos on a 2WD buggy :) I've been around in the hobby since my first electric RC10 and the entire thing ran off less capacity and way older NIMH packs than this 5,000Mah hump pack (in terms of battery chemistry advancements over the past 30 years :p) - you can easily expect minimum 5c but more likely 10C discharge rate out of that DDM pack; meaning you should be able to pull 25 - 50amps out of that thing which is absolutely more than enough. Again with telemetry on your radio right in your hands ... you don't need to rely much on the "ohh, seems like the steering response is a bit slower ... time to come in" for low power worries.

IMO there's a lot of information out there that's just plain wrong, or way overkill ... though you can't argue too much against being on the side of safety really. The kill switch to me is the must have, but even then ... I've never had a runaway short of funny enough .. also the Primal RC monster truck :p even with a kill switch installed, though it only coasted about 5 feet before it came to a stop.

"*NOTE: Certain combinations of receiver and ESC have been found to cause "Brown Out" issues when combined with Savox servos."
 
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Yes I have had a savox servo on a 1/10 22t race truck, it was so fast that if you did unreal driving tests like turning the steer right left repeatedly(to show of its speed) after several turns it would just stop! Let go of the steering and then it would work again. There was two fixes for this, a glitch buster(small capacitor plugged into a free receiver slot) or better, direct power the servo to the switch and just the signal wire needs to go to receiver. Again that was during abnormal use of the servo causing the extra load
There's alot of products on the market, if you get all the cheapest stuff , maybe you'll get what you want , if you buy all the top of the line, hey you might be unlucky and get a dud in the mix. It all depends on what you expect from your finished product. But there's never a guarantee of risk free
 
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Wheeeew! Super appreciate all for the deep input on RX batteries and servos everyone. I think I'll try this Ni-Mh battery first and see how it goes, and indeed upgrade it later. A few weeks ago when I was ordering all the stuff and wanted clarity on a few things, I called DDM and spoke to Steve. He was the one who steered (lol!) me towards these specific servos and battery, for whatever that's worth. I'll keep it charged every session to start. CHECK on the killswitch... probably the super bee.

Otherwise I'm two nights into building. First night was really unpacking everything and getting oriented, and second night things are coming along and catching the vibe of the manual. Really in no rush at all.

It's all super well designed and manufactured. The guidance on identification of parts is the main time suck thus far. Straight out of the gate the the manual had an error on a part location... or it was just packed wrong. Found it... but simply finding the right part on the trees is a bit of an adventure. Then trimming and grinding off the remaining little plastic nubs smooth with a Dremel.

Onward!

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LIFE GETS IN THE WAY OF BUILDING RC CARS... APPARENTLY.

...but a solid Sunday rainy day "old man" activity.

Admittedly I'm new to this. And probably talking to myself here, but things I've learned...

-The organization and management of the parts during assembly is paramount. The process of identifying and keeping track of the parts is almost the most important part of the entire process. Keep everything clean, orderly, and almost manically laid out.

-The more space the better. Laying out all the parts bags and trees so you can see them all at once... without having to rifle thru a pile... is super helpful.

-Review the step you are on in the building instructions first. Then review it again. Then review it again. Maybe one more time. The instructions are "good", but not great. They seem to be written by design engineers, rather than assembly "trainers". Some of the descriptions, and specifically the angles of illustrations are vague... which have sent me down some head scratching sessions, when something was one way... when it really looked another way. Overall good still.

-Having a ton of fun! Clearly... in no rush.


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